Anthony G. Francis, PhD, has compiled The Centaur Compendium. There is a lot here, such as a list of contemporary books where Centaurs play an important role, to a diagram of what a Centaur Skeleton might look like.

Lots of links of Classical texts relating to centaurs, as well as Greek art and vases with Centaurs, at this site: Classical Centaurs

Scroll down to the middle of this page, and you will see a picture of a remarkable tile mosaic with two female Centaurs: African Centaurs of Aphrodite

I love this site! Kathleen Jenks, Ph.D., has links to mythology sites all over the web at a site she calls MYTH*ING LINKS.
And she has as a page of particular interest to Centaur afficianado's....check out her Centaur links

Another one of the best sites in existance for mythologies from many, many different cultures is The Encyclopedia Mythica